State Police dive team members along with detectives gather around a backpack that was pulled up from the Messalonskee Stream near the North Street Bridge in Waterville on Friday, Feb. 3, 2012. The backpack contained items that led police to believe it belongs to a Waterville High School student from 2006. They also found an opened safe and a knife. They determined neither were related to the Ayla Reynolds case.

Curious motorists stop on the North Street Bridge in Waterville, at times causing a traffic jam, to catch a glimpse of State Police Dive Team Members as they searched the waters of the Messalonskee Stream for Ayla Reynolds who has been missing since Dec. 17, 2011. Some motorists hollering out open car windows yelled, "Did they find her yet?"

A State Police diver backstrokes to the shore after completing his shift searching the waters of the Messalonskee Stream in Waterville on Friday, Feb. 3, 2012 for Ayla Reynolds who has been missing since Dec. 17, 2011.

WATERVILLE, Maine — Investigators said Friday that their determination to find missing toddler Ayla Reynolds has not weakened even as the number of tips coming in from the public has begun to taper off.

Underwater searches of the Kennebec River and Messalonskee Stream throughout the day Friday turned up no new evidence in the case.

Lt. Kevin Adam of the Maine Warden Service said dive teams have been waiting for ideal weather in which to conduct more searches since teams scoured the river and stream on Jan. 11. He added that more searches of waterways and other areas will be conducted in the coming days and weeks.

“We found nothing related to Ayla today,” said Adam during a news conference Friday afternoon. “This search is systematic and it takes time.”

In the Kennebec River near the Donald Carter Bridge south of downtown, divers found a strongbox but didn’t take it from the water. In Messalonskee Stream, near the North Street Bridge, they found a knife and a former Waterville High School student’s black backpack with papers dating back to 2006.

Maine Department of Public Safety spokesman Stephen McCausland said none of those items are related to the missing toddler.

He categorized the search process as an effort to rule out areas where Ayla might be. He wouldn’t comment on whether any specific information led to the waterway searches. McCausland deflected numerous questions from reporters and offered no new information Friday in the case.

“We understand that the public has huge interest,” he said. “We want to keep the public informed as best we can but there are things that are appropriate to talk about and things that are not appropriate to talk about. We have no intention of releasing information piecemeal.”

He said police are holding out hope that Ayla is alive, but that their concern grows as time wears on.

McCausland said hundreds of items that were taken from 29 Violette Ave. in Waterville — the home of Ayla’s father, Justin DiPietro — are being examined at the State Police Crime Laboratory in Augusta.

Friday’s searches capped a dramatic week in the investigation. Investigators revealed a week ago — in response to releases of information from Ayla’s mother’s family — that the toddler’s blood had been found in the basement of the DiPietro house. Investigators also stated that they believe DiPietro and two other adults who were in the home on Dec. 16 — his sister Elisha DiPietro and his girlfriend, Courtney Roberts — have not told the whole truth about what happened to Ayla. The little girl has not been seen for 48 days. Her father reported her missing on Dec. 17, saying he put her to bed the night before and that she was nowhere to be found that morning.

Police have refused to say whether there are other witnesses who can attest that they saw Ayla before the night of Dec. 16. Her mother, Trista Reynolds, said the last time she saw Ayla was Nov. 21 and the last time she talked to her was about a week before the reported disappearance.

Waterville Police Chief Joseph Massey said a $30,000 reward for information leading to Ayla’s discovery is still available. Massey pleaded for someone with information to come forward.

“We know there’s someone out there who has some information,” he said. “If anyone has information, please call us and let us know.”

Anyone with information is asked to call Maine State Police at 624-7076.